Long draft spinning



April 8, 1941.

F. J. SCHIESSLER LONG DRAFT SPINNING File d Jan 25, 1940 v INVENTOR F. d. SCHIESSLER UNITED STATES PATENT OFFICE LONG DRAFT SPINNING Fred J. Schiessler, Cumberland, Md., assignor to Celanese Corporation of America, a corporation of Delaware Application January 25, 1940, Serial No. 315,463

6 Claims.

This invention relates to a drafting apparatus for the drafting of staple fibers and moreparticularly relates to the long or high drafting of these fibers.

An object of this invention is an improved drafting mechanism for the preparation of superior yarn from long staple fibers and, more particularly, yarns from long staples of artificial yarn. Another object of this invention is the preparation of the above-mentioned improved yarns with a minimum amount of variation -or modification in the usual drafting apparatus employed in the drafting of staple fibers.

The drafting of staple fibers has for its object the reduction of a mass of fibers of a given bulk to another mass of less bulk but of greater length. In this manner the fibers are drawn out into a form which is longer and thinner than the original form and the weight of the fibers per unit length is decreased to the desired degree. Such drafting is carried through a series of steps to a point where the reduction has proceeded to such an extent that the only remaining step in the treatment of the fibers is the imparting of a given twist to the yarn so that it will then be suitable for weaving into fabric.

It is essential that adrafting operation impart a considerable displacement to the individual fibers composing the roving which is being drafted. The advantages of such long drafting fibers to the bite of front rollers 3 and 6. Since rollers 3 and 6 are revolving at a greater speed than rollers 2 and 5 the roving is drafted and the fibers displaced with respect to each other. In this manner the bulk of the roving is reduced and a roving of lesser diameter produced. Rollers I 2 and 3, as well as rollers III, are soft and preferably covered with leather or similar material, while rollers 4, 5 and 8 are fluted steel rollers. The tension on leather apron 9 is controlled by floating roller 8 while the saddle i2 is used for applying weight to the top rolls l, 2 and 3 by means of rod ll, lever l4 and weight I! acting through rod l6 and anchored to the machine frame through rod IS.

The improvement of the present invention over drafting mechanisms known to the prior art resides in the relative positioning of front rolls 3 and 6 with respect to middle rolls 2 and 5 and the placing of the two control rolls Ill between the middle rolls 2 and 5 in a position back mechanism the lesser the number of drafts and I to obtain the ultimate draft desired. The compromise which has to be made in any instance in normal drafting practice is that between achieving a long draft and still maintaining the desirable qualities in the yarn produced. In every instance the qualities which'are aimed at in producing yarn by long drafting are evenness, regularity in weight of yarn per unit length, a good distribution of the short and long fibers and a regularity in the relative positions of the fibers. By means of the present improvement all these objects are attained while still achieving a desirable degree of draft.

In'the accompanying drawing, the figure represents a side view of the improved drafting unit. The roving is passed downward through back rollers I and 4 and thence to the bite of rollers III. The carrying apron then passes the The fibers are supported on apron 9 of the steel bar l3 which supports the apron 9.

In the ordinary drafting unit the usual means of controlling the roving between the front and middle rolls is a single roller riding on the apron and placed directly above bar l3. When this mechanism is used it was found that any unevenness which existed in the apron allowed the fibers that were being drafted to become loose and draft unevenly, The fibers were not controlled since no evenly distributed tension. was

maintained thereon as the apron and fibers passed between the roller and the bar l3. Since loose and'unco'ntrolled fibers were present the fibers draftedunevenly with slubs and weak points in the yarn frequently occurring. It was while seeking toremedy the defects of this arrangement that the improved arrangement of the'present invention was devised. Using this improved mechanism a greatly increased draft was attained and a substantial increase in the uniformity and strength of the yarn noted.

The novel improved arrangement of the drafting mechanism constituting the present invention consists in setting the front and middle drafting rolls at adistance from each other such that it is approximately about of an inch greater than the length of the staple which is being drafted and adding two control rolls for the fibers on the apron between the front and middle rolls. The intermediate control rolls Ill are placed on the apron as shown in the figure, one behind the other. The control roll closest to the front drafting rolls is set back away from bar ll. By so arranging the rolls, any unevenmass existing in the yarn or apron is compensated for by the constant pressure of the rolls I0 on the moving apron and on the roving. The feed of the roving to the nip of the front drafting rolls is therefore substantially constant and it is always under a uniform tension. Moreover, with this arrangement the fibers in the roving are under full control from the time they leave the bite of the middle rolls up to the time they are in the bite of the front rolls. With .such careful control possible throughout the entire drafting operation drafts from 20 to 35 can be successfully carried out with the resultant yarn being as strong and uniform and as equally free V from slubs as yarn produced by units using drafts as low as l3.

It is to be understood that the foregoing'detailed description is given merely by way of i1- lustration and that many variations 'may be made therein without departing from the spirit a of my invention.

Having described my invention, what I desire to secure by Letters Patent is:

1. In a mechanism for drafting rovings comprising artificial staple fibers, the combination of a set of front and middle drafting rolls, flexible means for supporting said roving between said middle and front drafting rolls, means for holding a portion of said flexible support in close proximity to said front drafting roll, means for contacting said roving positively at a plurality of points on said supporting means, the point closest to the front drafting rolls being behind the means for holding the flexible support in proximity to the front drafting rolls, and means for tensioning said flexible support,

2. In a mechanism for drafting rovings comprising artificial staple fibers, 'the combination of a set of front and middle drafting rolls, a moving apron for supporting said roving between'said middle and front drafting rolls, means for holding a portion of said apron in close proximity to said front drafting rolls, means for contacting said roving positively at a plurality of points on said moving apron, the point closest to the front drafting rolls being behind the means for holding the apron in proximity to thefront drafting rolls, and means for tensioning said apron.

3. In a mechanism for drafting rovings comprising artificial staple fibers, the combination of a set of front and middle drafting rolls, a flexible moving apron for supporting said roving between said middle and front drafting rolls, means for holding a portion of said apron in close proximity to said front drafting rolls, a plurality of rolls placed upon said moving apron and adapted to hold the roving being drafted under control, the roll closest to the front drafting rolls being behind the means for holding the apron in proximity to the front drafting rolls, and means for tensioning said apron.

4. In a mechanism for drafting rovings comprising artificial staple fibers, the combination of a set of front and middle drafting rolls, a flexible moving apron for supporting said roving between said middle and front drafting rolls, a bar for holding a portion of said apron in close proximity to the bite of said front drafting rolls, two rolls placed upon said moving apron and adapted to hold the roving being drafted under control, the roll closest to the front drafting rolls being behind said bar, and means for tensioning said apron.

5. In a mechanism for drafting rovings comprising artificial staple fibers, the combination of a set of front and middle drafting rolls, a flexible moving apron for supporting said roving between said middle and front drafting rolls, a bar for holding a portion of said apron in close proximity to the bite of said front drafting rolls, two rolls placed upon said moving apron and adapted to hold the roving being drafted under control, the roll closest to the front drafting rolls being behind said bar, and. a floating weighted roller for tensioning said apron.

6. In a mechanism for drafting rovings comprising artiflcia-l staple fibers, the combination of a set of front and middle drafting rolls set at an effective distance apart which is about 0.75 inch greater than the staple length of the fiber being drafted, a moving apron for supporting said roving between said middle and front drafting rolls, a bar for holding a portion of said apron in close proximity to the bite of said front drafting rolls, two rolls placed upon said moving apron and adapted to hold the roving being drafted under control, the roller closest to said front drafting rolls being in a positionbehind said bar, and a floating weighted roller for tensioning said apron.

FRED J. SCHIESSLER. 

